From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with ESMTP id 3C5D39000BD for ; Mon, 27 Jun 2011 05:45:13 -0400 (EDT) Received: from m3.gw.fujitsu.co.jp (unknown [10.0.50.73]) by fgwmail5.fujitsu.co.jp (Postfix) with ESMTP id 91D793EE0C0 for ; Mon, 27 Jun 2011 18:45:10 +0900 (JST) Received: from smail (m3 [127.0.0.1]) by outgoing.m3.gw.fujitsu.co.jp (Postfix) with ESMTP id 7B16245DE8F for ; Mon, 27 Jun 2011 18:45:10 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (s3.gw.fujitsu.co.jp [10.0.50.93]) by m3.gw.fujitsu.co.jp (Postfix) with ESMTP id 5628545DE9B for ; Mon, 27 Jun 2011 18:45:10 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id 4A4071DB803C for ; Mon, 27 Jun 2011 18:45:10 +0900 (JST) Received: from m105.s.css.fujitsu.com (m105.s.css.fujitsu.com [10.240.81.145]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id 0FD231DB8038 for ; Mon, 27 Jun 2011 18:45:10 +0900 (JST) Message-ID: <4E085113.7060200@jp.fujitsu.com> Date: Mon, 27 Jun 2011 18:44:51 +0900 From: KOSAKI Motohiro MIME-Version: 1.0 Subject: Re: [PATCH RFC] fadvise: move active pages to inactive list with POSIX_FADV_DONTNEED References: <1308779480-4950-1-git-send-email-andrea@betterlinux.com> <4E03200D.60704@draigBrady.com> <4E081764.7040709@jp.fujitsu.com> <4E084AA7.2030701@draigBrady.com> In-Reply-To: <4E084AA7.2030701@draigBrady.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: P@draigBrady.com Cc: andrea@betterlinux.com, akpm@linux-foundation.org, minchan.kim@gmail.com, riel@redhat.com, peterz@infradead.org, hannes@cmpxchg.org, kamezawa.hiroyu@jp.fujitsu.com, aarcange@redhat.com, hughd@google.com, jamesjer@betterlinux.com, marcus@bluehost.com, matt@bluehost.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org (2011/06/27 18:17), Padraig Brady wrote: > On 27/06/11 06:38, KOSAKI Motohiro wrote: >>> Hmm, What if you do want to evict it from the cache for testing purposes? >>> Perhaps this functionality should be associated with POSIX_FADV_NOREUSE? >>> dd has been recently modified to support invalidating the cache for a file, >>> and it uses POSIX_FADV_DONTNEED for that. >>> http://git.sv.gnu.org/gitweb/?p=coreutils.git;a=commitdiff;h=5f311553 >> >> This change don't break dd. dd don't have a special privilege of file cache >> dropping if it's also used by other processes. >> >> if you want to drop a cache forcely (maybe for testing), you need to use >> /proc/sys/vm/drop_caches. It's ok to ignore other processes activity because >> it's privilege operation. > > Well the function and privileges are separate things. > I think we've agreed that the new functionality is > best associated with POSIX_FADV_NOREUSE, > and the existing functionality with POSIX_FADV_DONTNEED. > > BTW, I don't think privileges are currently enforced > as I got root to cache a file here with: > # (time md5sum; sleep 100) < big.file > And a normal user was able to uncache with: > $ dd iflag=nocache if=big.file count=0 > Anyway as said, this is a separate "issue". I'm failed to see your point. Why does dd need to ignore other process activity? If no other process, this patch doesn't change any behavior. Isn't it? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org